Telecommunication cables are typically provided outdoors either overhead or buried in the ground. When splices to these cables must be effected, either for repair or further interconnection purposes, the spliced area [splice) must be protected against the environment.
A fully protected multiple conductor cable splice often has a protective casing which may be opened for splice purposes, newly-made connections or repair of prior connections. Closure of the casing subjects the cables again to moisture intrusion. Moisture which bridges connections or exposed conductors gives rise to faults which disrupt or otherwise undermine intended communication channels, requiring costly reopening of the spliced connection, trouble-shooting and correction thereof. Moisture susceptibility is heightened where the spliced connection is located underground or in another high moisture environment.
The prior art is replete with varied approaches to a solution of the moisture intrusion problem, generally falling into three categories.
In a first type of approach, the art has looked to the application of an electrically insulative fluid to the individual conductors and connections, the fluid being of a type which "sets" or generally solidifies with the passage of time, i.e., an encapsulant. In the interval between application and setting of the fluid, mechanical force is applied thereto to induce movement of the fluid fully into the interstices between the conductors and connections. In this first approach, the mechanical force is provided by pressure-wrapping a tape member over the fluid, with successive courses of the wrapping overlapping prior courses of the wrapping and with successive longitudinal wrappings often being applied. In a variation of this first type of approach, a flexible bag is configured over the cable length to be protected with the fluid being introduced by pouring it into the bag. The open portion of the bag is then folded over the remnant thereof and the tape member is applied to the bag. In either instance, a non-rigid outer enclosure is applied to the tape wrap and sealingly secured to the cable outwardly of the splice and, at times, also to the tape wrap.
While the described practice has been successfully implemented, applicability thereof has limitations. Thus, it is not useful in installations in which the completed splice is likely to be subject to mechanical force beyond that tolerable by the non-rigid outer enclosure of the splice.
The second approach involves the steps of the first approach through the tape wrapping step. Following that juncture, however, this approach departs in providing a rigid enclosure for the splice, typically in the form of a pair of mated semi-cylindrical shells sealably secured to one another and to end plates applied to the cables prior to making the splice. In a variation of practice in the second approach, the mechanical force to displace the fluid into the splice interstices, while derived in part from the wrapping, is derived in further part by interiorly pressurizing the rigid enclosure after sealing has been effected.
The second approach, while providing an assembly suited for the environments not met by the first approach, is evidently as labor intensive in requiring the wrapping practice, and further involves the additional step of pressurization of the wrapped subassembly.
In a third approach, the art has looked to the introduction of the encapsulating fluid under pressure within a rigid enclosure. This approach omits the wrapping step following the splicing. Rigid semi-cylindrical housings are applied and are sealingly joined to one another as in the second approach. The enclosure thus formed defines an inlet port to which a caulking gun type of device containing the encapsulant fluid is connected. The enclosure further defines a closed outlet port in which is seated a pop-up type pressure indicator. In the course of a user pumping the fluid into the enclosure, by repetitively refilling the caulking gun from a bulk container of the encapsulant fluid, a point in time is reached when the pressure indicator is activated and the assembly is then considered complete.
The third approach is seen as advantageous in its provision of both a rigid enclosure and in the introduction of the encapsulating fluid under pressure, with attendant likelihood of lessening voids, e.g., entrapped air bubbles possibly receptive of moisture. However, disadvantage is seen in the use of a closed outlet while pumping fluid into the enclosure under pressure. While air may escape before the outlet is closed, some air may remain in the enclosure which may mix with the encapsulant fluid to cause air pockets or bubbles in the fluid. Further, the described practice is seen as unduly labor-intensive and time-consuming in its requirement for repetitive retreat to the bulk encapsulant container. Still further, known sealing measures and structures in the prior art in respect of this third approach are seen as less efficacious than needed for satisfaction of industry demand.